The field of the present invention is soundproof engine working machines of the type comprising a soundproof casing containing an engine and a working machine such as a dynamo, a compressor and the like driven by the engine.
Engine working machines in which an engine and a working machine such as a dynamo, a compressor, etc. driven by the engine are unified are generally used at construction sites. These frequently employ a soundproof type structure, in which the entire equipment is covered with a soundproof casing in order to maintain the running noise as low as possible.
In a soundproof engine working machine of this kind, the ports through the casing such as an air inlet port, an exhaust port, etc. are made as small as possible in order to minimize noise as mentioned above. Since the openings are small in size, cooling of the inside of the soundproof casing, and particularly in an air cooled type wherein cooling water is not used, is difficult as is positioning of heat emitting devices such as engine, muffler, dynamo, etc. in relation to other devices and cooling systems.
Due to the foregoing, cooling fans driven by engines have been provided within such soundproof casings. Such devices are then ventilated by such cooling fans. For example, in Japanese Laid-open utility model publication No. Sho 58-109519, there is disclosed a soundproof type engine dynamo wherein an engine and a dynamo are provided with cooling fans. In this soundproof type engine dynamo, cooling air produced by the dynamo cooling fan is, after it has cooled the dynamo, introduced to an air duct provided on an under surface of a crankcase of the engine to cool the under surface of the engine. The cooling exhaust air passed through the air duct is attracted by the engine cooling fan together with the air which has cooled the cylinder portion of the engine and is exhausted outside through an exhaust duct.
A similar soundproof type engine working machine is also disclosed in Japanese Laid-open utility model publication No. Sho 56-49234. In this engine working machine, cooling exhaust air forced to flow along an under surface of a crankcase by a dynamo cooling fan in the same manner as described above is joined with the engine cooling exhaust air discharged by an engine cooling fan and exhausted outside.
However, in such a soundproof type working machine wherein the cooling exhaust air at the working machine side and the cooling exhaust air at the engine side are joined and exhausted together, unless performance characteristics of the working machine cooling fan and the engine cooling fan are properly adjusted together, the streams of air do not flow smoothly. This can often result in lower cooling effects for either the working machine or engine or both.
For example, in the first described engine dynamo, if the air flow of the dynamo cooling fan is too great, the amount of cooling air for the cylinder portion attracted by the engine cooling fan becomes so small as to lower the cooling effect for the cylinder portion. On the other hand, in the second described engine dynamo, if the discharge air pressure of the engine cooling fan is too high, the flow rate of the dynamo cooling fan is restricted by the high pressure and reduces the amount of the cooling air for the dynamo and the lower portion of the crankcase. This often results in lowering cooling efficiency for these portions.
Although the above-mentioned conventional machines employ suction fans, similar problems exist in machines of the type which employ forcing fans for forcing cooling air into an engine or dynamo.
Further, there is known, by Japanese utility model publication No. Sho 44-3686, a soundproof type engine in which a duct for covering the cylinder head of an engine and a muffler is provided. Cooling air is force-ventilated by a fan through the duct. The cylinder head and the muffler are cooled and the heated air is discharged outside of a soundproof casing. This soundproof type engine is not integrally formed with a working machines and, as a matter of course, does not include a cooling means for the working machine. Also, in this soundproof type engine, no consideration is given to cooling with respect to an oil pan in a lower portion of the crankcase. However, when an engine is large, cooling with respect to the oil pan portion is desired. In this engine, if the oil pan portion is cooled by cooling air which is force-ventilated through the duct, there arises the problem that ventilation resistance is increased and sufficient cooling is not effected unless the discharge pressure of the fan is increased.
In the aforementioned engine working machines, there are cases where a recoil starter is required which in turn requires a starter motor. These components require additional space in the case. A space may then be required for installing a battery to serve as a power source of the motor. In conventional soundproof type engine working machines, the battery is situated at a rear location of a main body of the engine working machine as shown, for example, in Japanese utility model publication No. Sho 51-23016. Alternatively, the battery may be separately situated from the main body of the engine working machine to avoid cooling problems as shown, for example in Japanese utility model publication No. Sho 59-39151. With such systems where a recoil starter is employed with a soundproof type engine working machine, it is unavoidable that the entire machine becomes large in bulk.